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Is There A Dementia Prevention Diet?

Dementia is a leading disability and the seventh cause of death in the elderly.1 In 2015, 47 million people were diagnosed, and this number is estimated to triple in the next 30 years.2

With the high prevalence of this disease and no effective treatments, special attention is paid to identifying and influencing the risk factors for this disease.

In addition, finding methods like a possible dementia prevention diet is a priority. 

Dementia nutritional deficiencies

According to the 2020 Lancet Commission on Dementia Prevention, Intervention, and Care report, 40% of dementia cases are attributable to modifiable risk factors. The main modifiable risk factor is dietary.2  

Vitamin D, B9 (folate), and B12 deficiencies are associated with dementia.4,5 Consumption of foods rich in saturated fatty acids (fats that are solid at room temperatures like butter, cheese, and red meat) increases the risk of dementia.4, 5

Consumption of poly and monounsaturated fatty acids (fats that are liquid at room temperatures, such as olive or peanut oil) have a protective effect.4, 5

The Mediterranean diet makes up for these deficiencies and systematically has a mild saturated fat intake. The Mediterranean diet is characterized by the high consumption of plant-based foods and healthy fat sources like 

  • fruits, 
  • vegetables, 
  • whole grains, 
  • legumes, 
  • nuts and seeds,
  • olive oil,
  • and consumption of animal protein like fish.6

However, studies linking this diet to a lower risk of cognitive decline and dementia have produced conflicting results.2,4

To help reduce confusion around the issue of diet and dementia, Swedish scientists conducted a large observational study, i.e. a study in which subjects were followed up without any intervention.2

The dementia diet study 

Experts studied the data of approximately 28,000 people. At the beginning of the study, the subject’s average age was 58.

The participants regularly provided data on their diet in the form of a weekly food diary, and a detailed questionnaire on the frequency and amount of consumption of various foods and were interviewed about eating habits.

Based on the logs and questionnaires, the research team “scored” each participant on their adherence to the recommended standard Swedish dietary guidelines, a version of the Mediterranean diet.2


Over the next 20 years, 1943 people, or 6.9% of participants, were diagnosed with some form of dementia. Two types of cognitive impairment were taken into account.

  1. Dementia associated with Alzheimer’s disease.
  2. Vascular dementia, which occurs due to poor blood flow to the brain.2

The results of the dementia prevention diet study showed that participants who followed a traditional Swedish or Mediterranean diet did not have a lower incidence of either type of dementia than participants who did not follow both dietary plans.

The experts also found no association between diet and a specific marker of Alzheimer’s disease, which they tested in about 740 participants with cognitive decline.2

Does it mean that diet has no influence on dementia?

Similar to previous research relating to dementia prevention diet risk and outcomes, the Swedish study has its limitations. Scientists cannot strictly monitor adherence in a long-term study of eating habits that occur outside of a controlled setting.

The lack of study control means the results are challenged by confounding factors like changing dietary habits, lifestyle changes, or the emergence of new comorbidities over time.

Research on nutrition intake and lifestyle factors shows a high level of discrepancy between fact and fiction in participants’ food and lifestyle diaries.2

Swedish researchers do not refute the idea of a link between diet and dementia. The researchers found that diet alone does not affect the course of cognitive function and dementia risk later in life.

Other variables like regular exercise, not smoking, continuously challenging the brain, drinking in moderation, and keeping your blood pressure under control are also components to consider for reducing the risk of cognitive decline and dementia .2, 7


  1. World Health Organization. Dementia. World Health Organization. Published 2023. Accessed April 2, 2023. https://www.who.int/news-room/fact-sheets/detail/dementia
  2. Glans I, Sonestedt E, Nägga K, et al. Association between dietary habits in midlife with dementia incidence over a 20-year period. Neurology. October 12, 2022:10.1212/WNL.0000000000201336. doi: https://doi.org/10.1212/wnl.0000000000201336
  3. Livingston G, Huntley J, Sommerlad A, et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. 2020;396(10248):413-446. doi:10.1016/S0140-6736(20)30367-6
  4. Del Parigi A, Panza F, Capurso C, Solfrizzi V. Nutritional factors, cognitive decline, and dementia. Brain Research Bulletin. 2006;69(1):1-19. doi: https://doi.org/10.1016/j.brainresbull.2005.09.020
  5. Shreeya S Navale, Anwar Mulugeta, Ang Zhou, David J Llewellyn, Elina Hyppönen, Vitamin D and brain health: an observational and Mendelian randomization study, The American Journal of Clinical Nutrition, Volume 116, Issue 2, August 2022, Pages 531–540, doi: https://doi.org/10.1093/ajcn/nqac107
  6. The Mediterranean diet: A guide to healthy eating. Dieticians of Canada. https://www.dietitians.ca/DietitiansOfCanada/media/Documents/Mediterranean%20Diet%20Toolkit/Mediterranean-Diet-Toolkit-A-Guide-to-Healthy-Eating-(handout).pdf. Published October 4, 2017. Accessed April 7, 2023. 
  7. Preventing Alzheimer’s Disease: What Do We Know? National Institute on Aging. Published 2018. Accessed April 2, 2023. https://www.nia.nih.gov/health/preventing-alzheimers-disease-what-do-we-know
Olga Ciciu BSc
Olga Ciciu BSc
Olga Ciciu is a medical columnist for the Medical News Bulletin. She graduated from the University of Montreal with a bachelor's degree in Biopharmaceutical Sciences. She has expertise in the pharmaceutical industry and clinical epidemiology, which she further developed through her work as a Research Assistant and Drug Research and Development Consultant.


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